Semiconductor technologies are continually progressing to smaller feature sizes, for example down to feature sizes of 22 nanometers (nm) and below. A patterned photoresist layer used to produce such small feature sizes typically has a high aspect ratio. However, maintaining a desired critical dimension (CD) can be very difficult for various reasons, especially for a resist layer with a high aspect ratio. Thus, multiple patterning techniques, such as using two or more masks per layer pattern, have been introduced to form various features with smaller dimensions. However, not all layer patterns can be resolved into a predefined number of masks.